Discussion: Asteroid Threat Upgraded to 1 in 45

[Fraser]

SUMMARY: The probability that Asteroid 2004 MN4 will strike the Earth on April 13, 2029 has actually been upgraded to a 1-in-43 chance now that more observations have been made. The asteroid has reached an uprecedented 4 on the Torino scale. Of course, this still means that there's a 98% chance that it'll completely miss the Earth. The space rock is 400 metres (1,300 feet) across, so a direct impact with our planet would cause a significant amount of damage on a regional level.

What do you think about this story? Post your comments below.

[Pär]

Is this scenario possible?:

We mount thrusters on MN4. Direct it into orbit around earth. We use it as a shield in front of future space stations and even use its materials.

[Greg]

This would be a nice candidate for mining for raw materials such as radiation shielding for orbiting space stations. I would liken it to a really nig aircraft carrier in space. The practical value of using in such a fashion isn't relevant now, but will become relevant within a century I would guess. OF course your question becomes moot.
The impact of this thing would be devastating if it hit in a populated region. Fortunately the accuracy of these things arent the same as a precision as a RT-23 (Scalpel) Russian ICBM, so the main threat actually would be to coastal regions opposite a likely water impact. If I were you I would not plan to be anywhere near the ocean if you are still around on that date. Or if you become tired of life by then, maybe you should book advanced reservations for Hawaii.
FYI if anyone asks the 1908 hit was in Tungusta (Siberia.) The object was estimated to have been 40-60 meters in diameter, but likely was a conglomeration of material rather than a solid object, since no impact crater was left. The object disintegrated in the atmosphere, but the shock wave from that leveled a 15km area with an equivalent force of a small nuclear weapon (est 2-3x the hiroshima bomb).
I am pleased that the media has not hyped this up yet as badly as previous detections. But I predict that it is a matter of time before this gets significant hype and media attention in some circles I just hope the big networks have learned their lessons by now.

[Greg]

Sorry I didn't have a chance to proofread my last post. To clarify, the question becomes moot if the object slams into the Earth.
One thing I would like to ask is the link to a website that allows one to calculate the damaging effects of meteorite impacts. I seem to have lost it, it has been at least 6 months since that article was published, I think at a major SW USA university.

[alan]

This what you are looking for?
http://www.lpl.arizona.edu/impacteffects/

[Moseley]

That's great - only took a little imagination to end up with Earth forming a new asteroid belt between Venus and Mars - didn't sound too likely though.

[Guest]

....significant amount of damage on a regional level

this would be terrible

[Fraser]

Here's me standing about 100 km away from the strike.

Your Inputs:
Distance from Impact: 100.00 km = 62.10 miles
Projectile Diameter: 400.00 m = 1312.00 ft = 0.25 miles
Projectile Density: 3000 kg/m3
Impact Velocity: 17.00 km/s = 10.56 miles/s
Impact Angle: 45 degrees
Target Density: 2500 kg/m3
Target Type: Sedimentary Rock

Energy:
Energy before atmospheric entry: 1.45 x 1019 Joules = 3.47 x 103 MegaTons TNT
The average interval between impacts of this size somewhere on Earth during the last 4 billion years is 5.9 x 104years

Atmospheric Entry:
The projectile begins to breakup at an altitude of 54000 meters = 177000 ft
The projectile reaches the ground in a broken condition. The mass of projectile strikes the surface at velocity 15.6 km/s = 9.71 miles/s
The impact energy is 1.23 x 1019 Joules = 2.94 x 103MegaTons.
The broken projectile fragments strike the ground in an ellipse of dimension 1.26 km by 0.893 km

Major Global Changes:
The Earth is not strongly disturbed by the impact and loses negligible mass.
The impact does not make a noticeable change in the Earth's rotation period or the tilt of its axis.
The impact does not shift the Earth's orbit noticeably.

Crater Dimensions:
What does this mean?


Crater shape is normal in spite of atmospheric crushing; fragments are not significantly dispersed.

Transient Crater Diameter: 4.99 km = 3.1 miles
Transient Crater Depth: 1.76 km = 1.1 miles

Final Crater Diameter: 6.19 km = 3.84 miles
Final Crater Depth: 0.512 km = 0.318 miles

The crater formed is a complex crater.
The volume of the target melted or vaporized is 0.0774 km3 = 0.0186 miles3
Roughly half the melt remains in the crater , where its average thickness is 3.96 meters = 13 feet

Thermal Radiation:
What does this mean?


Time for maximum radiation: 0.295 seconds after impact

Visible fireball radius: 3.83 km = 2.38 miles
The fireball appears 8.71 times larger than the sun
Thermal Exposure: 4.61 x 104 Joules/m2
Duration of Irradiation: 6 seconds
Radiant flux (relative to the sun): 7.68


Seismic Effects:
What does this mean?


The major seismic shaking will arrive at approximately 20 seconds.
Richter Scale Magnitude: 6.9
Mercalli Scale Intensity at a distance of 100 km:

VI. Felt by all, many frightened. Some heavy furniture moved; a few instances of fallen plaster. Damage slight.

VII. Damage negligible in buildings of good design and construction; slight to moderate in well-built ordinary structures; considerable damage in poorly built or badly designed structures; some chimneys broken.


Ejecta:
What does this mean?


The ejecta will arrive approximately 144 seconds after the impact.
At your position the ejecta arrives in scattered fragments
Average Ejecta Thickness: 5.54 mm = 0.218 inches
Mean Fragment Diameter: 3.85 cm = 1.52 inches


Air Blast:
What does this mean?


The air blast will arrive at approximately 303 seconds.
Peak Overpressure: 15200 Pa = 0.152 bars = 2.16 psi
Max wind velocity: 33.8 m/s = 75.6 mph
Sound Intensity: 84 dB (Loud as heavy traffic)
Damage Description:


Glass windows will shatter.

[Greg]

That was the link I was looking for, thanks.

Nobody yet has asked the obvious question, if this object is on a collision course for Earth, then should we attempt to blow it into smaller pieces using nuclear weapons? Would it not be better to have hundreds of smaller impacts than one devastating one? What if it were projected to hit Russia and they decided to unilaterally strike it with nuclear weapons, resulting inevitable in some of the debris hitting the USA? Or vice cersa?
Another big question I would like to have answered is what kind of water damage would an ocean strike deliver via Tsunamis to nearby islands and adjacent coastal regions? Is there a website that can calculate that kind of impact? This is particuarlly fitting considering the horrible global tradgedy from the 8.9 earthquake that hit off the coast on Indonesia and the Tsunamis resulting from it. My condolences to anyone affected by that catastrophe.

[zrice03]

Would it not be better to have hundreds of smaller impacts than one devastating one?

Actually, it's better to get hit by one large impact. If the Earth were hit by "buckshot" the damage would be far more widespread. A single impact causes more localized damage, but much of the energy is "wasted" at the impact site.

I like the idea of changing the trajectory so that it would orbit the Earth, but the problem is: how do we do that? According to Wikipedia's Page, the asteroid will pass by (or hit) at 12.69 km/s. Fortunately, this is quite low for objects traveling at interplanetary speeds. We'd have to slow it down about 6-8 km/s to make it orbit Earth.

I suggest using nuclear weapons near (but not on&#33 the asteroid to nudge it. I haven't done the math, but I would assume it would take quite a few (maybe 50-100) over a time span of 10-15 years.

Once in orbit, we can mine it, as was suggested before.

Another Problem: The Comprehensive Ban Test Treaty forbids nuclear explosions in any environment (including space). But, with such a huge benefit for humanity it shouldn't be to hard to get the U.N. to override it. It could be quite ironic, actually, using weapons of mass destruction to save millions of people and/or greatly improve the Space Program.

[Guest_senmut]

1.This is serious warning for Florida, Bahamas, Bermudas, Carribean states...!
Probability of earthquake followed by tsunami (how it was hours ago in Indonesia, Sri Lanka...) is high!
Weaker earthquakes continue in that (Indic Ocean) area till now!
Be ready and watch carefully situation!
Sorry for placing of this warning here...

2.There was earthquake which followed bright meteorit (bolid) which was seen (some days ago) on sky (Indonesia) in this area!!!???
Maybe that one (meteorit) wasnt only one, but there were more such pieces, which fallen into Indic Ocean...?! and ignited forces for earthquake??!!

[Greg]

I am not aware of any meteroite impact associated with the massive earthquake near Indonesia. A meteorite hit generating that size of an earthquake would not have been missed and would have caused far more damage. It is beyond doubt that the natural disaster was caused by an underground earthquake along a fault line most likely associated with a subduction zone off the western shore of Indonesia.

[Guest_Spacemad]

Originally posted by Greg@Dec 26 2004, 08:26 PM

Another big question I would like to have answered is what kind of water damage would an ocean strike deliver via Tsunamis to nearby islands and adjacent coastal regions? Is there a website that can calculate that kind of impact? This is particuarlly fitting considering the horrible global tradgedy from the 8.9 earthquake that hit off the coast on Indonesia and the Tsunamis resulting from it. My condolences to anyone affected by that catastrophe.

I think you have partially answered your own question, Greg. Although it is a terrible tragedy for all those involved/affected I think the tsunami that affected the rim of the Indian Ocean would give some indication as to what might happen if an object, such as the one described in this article, were to strike the oceans of the world!! I don´t know if a surface impact would be worse than the "accident" that happened on the seabed, I presume the displacement of millions of cubic metres of seawater would produce a tsunami much greater than that of this Christmas weekend - one that might run around the Earth itself(?) (Or might that be an exaggeration?)

I would also like to extend my condolences to everyone caught up in this terrible tragedy.

[Leo]

Now it is 1:37 a slowly increasing:

http://neo.jpl.nasa.gov/risk/2004mn4.html

Leo

[TheThorn]

This page:
http://www1.tpgi.com.au/users/tps-seti/spa...l#tsunamiimpact

is likely interesting to those speculating about the effects of a tsunami coming from an asteroid impact. At first glance, it sounds like a tsunami from an asteroid this size would be very serious, but not much world threatening. Probably not much worse than the catastrophe the other day (which is quite bad enough, thanks).

OTOH, if this asteroid does cause such a wave, we'll know exactly where, and to split second timing, years in advance. Of course there will be some people who want to stand on the beach to watch it, but it isn't going to catch anyne by surprise.

[Greg]

Thanks, Thorn. I purused the site and came up with some useful inofmation to post. BTW this is a great website for this topic. Apparently the defense department has already studied this question in detail. During the cold war they considered the possibility that the USSR or China might deploy a nuclear bomb and explode it offshore in international waters in order to inundate the coastline with a massive tsunami, potentially wiping out everyone in coastal cities. Apparently they did some experiments to see just what effect a small nuclear explosion would have on propagating ocean waves. (Impact craters in fact would behave in a very similar fashion as a nuclear explosion in the water.) What they found (and this was only relatively recently declassified) should be of great relief to us all.
Waves generated by explosions like a nuclear bomb (and small-mid size meteorite impacts) create high amplitude waves. These behave in a totally different fashion than low amplitude (but high energy) waves created by earthquakes. They mention an effect first described by Van Dorn whereas the vast majority of the energy of these waves will dissipate on the offshore shelf runup and never reach the shoreline. If you have ever surfed you would know that high amplitude "chop" waves do not reach the shoreline whereas low amplitude waves do. They would be a significant hazard to shipping offshore, but essentially no threat to people inland. The opposite is true for earthquake generated waves which do not break offshore and are no risk to ships offshore (unless they are immediately near the coastline) but present a significant hazard to people on the shoreline.
The picture changes once the meteorite exceeds the size of 1000m however. These would be capable of generating waves hundreds of feet high due to the characteristics of the impact crater acting more like an earthquake. Needless to say this big of a wave would reach shore and do considerable damage. The expected wave size of an impact on the scale of 200 meters would be about 3 meters. According to the defense department this would harmlessly break offshore and likely would never reach the shoreline. But I would not want to be deep sea fishing the day of a small meteorite impact, however.

[Kev]

Looking at that impact tsunami page carefully seems to suggest that something this size would be MUCH worse than the recent earthquake tsunami, as the figures of between 2 and 15 meter wave height are the deep water figures and surely they get much bigger once they hit shallow water?

[Greg]

As I mentioned above, the type of wave propagated would be of higher amplitude and crash on the shelf runup to shore and dissipate there rather than run to the shoreline and break there like an earthquake generated tsunami.

[Guest]

Is this still true if it came down in shallow water?

[Guest_jim]

It might be interesting if someone could state the odds of the asteroid hitting the moon and what the effects of that would be

[Guest_Adrian]

IMPACT PROBABILITY HAS INCREASED!!

Impact Probability is now 2.7%

or

1 in 37 chance

The impact probability just sems to be higher and higher for every day!

Neo, NASA, Impact risk for 2004 MN4

Remember that 2,7% is a high number when you play with the death!

[TheThorn]

And just as quickly, it is now down to TS 0.

They found some "pre-covery" observations in the Spacewatch archives from last year, and that refined the orbit enough to rule out a collision in 2029.

http://neo.jpl.nasa.gov/news/news148.html

[alan]

odds now 1 in 56000

[antoniseb]

Originally posted by TheThorn@Dec 28 2004, 12:42 AM
And just as quickly, it is now down to TS 0

That is excellent, but not surprising news.

[Guest]

I don't think this story is over yet. As I see it the uncertainty in the miss distance in 2029 means that the orbit beyond that is almost impossible to predict, and will be for a couple of years. Better data on 2004 MN4's orbit will help, but what is really needed is to find out what it is made of, and whether it is really two (or more) objects not one.

Passing this close to earth may result in 2004 MN4 being pulled apart, just like Shoemaker-Levy 9 at Jupiter. All of the resulting objects will likely eventually hit earth--for some large value of eventually. Some parts may hit the earth as early as the following year. See here for details: http://neo.jpl.nasa.gov/risk/2004mn4.html

My guess at this time is that doing something before 2029 is going to be a very good idea. Putting a nuclear weapon in the middle and putting the two halves in different orbits may be workable. That seems very hazardous as a plan with this much warning. Plenty of time to put a high efficiency ion engine on 2004 MN4 and move all of it (very slowly so pieces don't come off) into an orbit that does not intersect the earth's orbit.

It could also be redirected to hit the moon, but again that is a risky plan. Some of the ejecta would hit the earth, and it would be impossible to predict that all the ejecta would be small.

[Adrian Gregory]

The most likely scenario is that the earth will be hit of a big astroid, soner or later, without any warnings. Most near earth objects has not ben detected.

[antoniseb]

Originally posted by Adrian Gregory@Dec 28 2004, 12:56 PM
The most likely scenario is that the earth will be hit of a big astroid, soner or later, without any warnings. Most near earth objects has not ben detected.

<irony>This message is such a beacon of hope and good cheer&#33;</irony>

The current claim is that we have discovered the majority of the Earth crossing asteroids larger than 500 meters. It is true that another 30% of them remain undiscovered, but they will soon be found, and the technology to move them can be developed fast enough to save us if any are on a collision course.

If you have a worry, it is the rare long period comet, or a nearby GRB.

[cleetus]

:huh: :ph34r: :ph34r: :huh: :huh: its only a matter of time b4 we get adirect hit like siberia 1908 & its time we put an action plan in place in case we find an astroid thatill hit us :blink: :( :huh: :o :rolleyes: :rolleyes: :rolleyes: :rolleyes: :rolleyes: :ph34r: :ph34r: :blink: :blink: :unsure: :unsure: :unsure: :) :) :angry: :angry: :angry: :( :( <_< <_< <_< <_< <_< <_< :rolleyes: :rolleyes: B) B) :P :P :D :D :lol: :lol: :huh: :huh: :huh: :huh: :huh: :huh: :huh: :huh: :huh: :huh: :huh: :huh: :huh: :huh: :huh: :huh: :huh: :huh: :huh: :huh: :huh: :huh: :huh: :huh: :huh: :o :o

[Brandon2004]

I&#39;ve got a small qustion. Have you got any links to websites where i can find photos of 2004 MN4 or mayby you have got some photos. Please send it to me.
My brandonnurek@tlen.pl

[antoniseb]

Originally posted by Brandon2004@Dec 28 2004, 07:18 PM
Have you got any links to websites where i can find photos of 2004 MN4

Any images will simply be of short very narrow streaks through star fields. This object is too tiny and too distant to show up as more than one pixel in any system currently observing. We could get an image of it using a satellite, like NEAR, or we can wait till April 13th, 2029.